Semiconductor device and manufacturing method thereof

ABSTRACT

A semiconductor device packaged in three dimensions comprises a first thin film device, a second thin film device, and a third thin film device, each of the first, second, and third thin film devices comprising a first insulating film, a first electrode formed over the first insulating film, a second insulating film formed over the first electrode, first and second thin film transistors formed over the second insulating film, wherein the first thin film transistor is connected to the first electrode through a first contact hole, a third insulating film formed over the first and second thin film transistor, a second electrode formed over the third insulating film, wherein the second electrode is connected to the second thin film transistor through a second contact hole, and a fourth insulating film formed over the third insulating film and the second electrode.

This application is a divisional application (and claims the benefit ofpriority under 35 U.S.C. § 120) of U.S. application Ser. No. 10/728,903,filed Dec. 8, 2003, now U.S. Pat. No. 7,109,071, and U.S. applicationSer. No. 09/951,384, filed Sep. 14, 2001, now U.S. Pat. No. 6,682,963,which claims priority under 35 U.S.C. § 119 from Japanese ApplicationNos. 2000-280864 and 2000-280902 filed in Japan on Sep. 14, 2000. Thecontents of the prior applications are incorporated herein by referencein their entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method of manufacturing asemiconductor device, and in particular, it relates to a method ofmanufacturing a thin, flexible (having a flexible property)semiconductor device. Further, the present invention relates to a methodof reducing parasitic capacitance which is generated between wringsformed on differing layers through insulating films. Note that the termsemiconductor device in this specification indicates general deviceswhich function by utilizing semiconductor properties, and that inparticular, the present invention can be suitably applied to integratedcircuits using elements having SOI (silicon on insulator) structures inwhich a semiconductor layer is formed on an insulator, to active matrixliquid crystal display devices structured using thin film transistors(TFTs), to active matrix EL display devices, and the like. The term thinfilm device indicates an electronic device containing a thin filmtransistor (TFT) structured using a semiconductor thin film, and atleast one element from amount elements such as wirings, conductivelayers, resistors, and capacitive elements in this specification.

2. Description of the Related Art

Integrated circuits using elements having SOI structures in whichsemiconductor layers are formed on an insulator exist as one kind ofsemiconductor device. It is possible to have little parasiticcapacitance, and to have high operation speed, by forming semiconductorlayers on insulators.

One type of semiconductor device is an active matrix liquid crystaldisplay device. Structures in which a substrate on which thin filmtransistors (TFTs) are formed and used as switching elements of pixels(TFT formation substrate), and a substrate on which an opposingelectrode is formed (opposing substrate) are joined, and liquid crystalsare injected in a gap between the substrates, is prevalent for activematrix liquid crystal display devices. The voltage applied to the liquidcrystals can be controlled for each single pixel by the TFTs formed on atransparent substrate such as glass, and therefore active matrix liquidcrystal display devices have clear images and are widely used in officeautomation equipment, televisions, and the like.

Further, active matrix EL display devices are known as one type ofsemiconductor device. Active matrix EL display devices have a structurein which an EL material is sandwiched between two electrodes, and anelectric current flows, thereby causing light to be emitted. Theelectric current flowing in the EL material can be controlled for eachsingle pixel by using a plurality of pixel transistors, and therefore animage is clear.

The level of integration for these types of semiconductor devices isincreased and becoming minute. Parasitic capacitance which is generatedbetween wirings of a semiconductor device leads to electric signalpropagation delays, and this hinders high speed operation and accurateelectric signal propagation. There are two types of parasiticcapacitance, one which is generated between wirings formed on the samelayer, and one which is generated between wirings formed on differentlayers through an insulation film.

If the level of integration is increased, the distance between wiringsformed on the same layer becomes smaller, thereby increasing theparasitic capacitance. Wirings may be moved to different layers in orderto reduce the parasitic capacitance between wirings formed on the samelayer. Namely, the integration level of wirings on the same layer isspread among several layers. Lowering the parasitic capacitance which isgenerated between wirings formed on different layers, through aninsulation film, contributes to an improvement in the overallintegration level of the semiconductor device.

There are methods such as making, insulation films thicker andincreasing the distance between wirings, and using insulation filmshaving a low dielectric constant, in order to reduce the parasiticcapacitance generating between wirings formed on different layersthrough an insulation film. However, if the insulating film is madethicker, then not only does it become more difficult to form an openingportion in the insulation film in order to make a conductive connectionbetween wirings, but there are also cases in which problems such asconductive layers formed by sputtering, for example, breaking in theinside of the opening portion, or being unable to ensure a sufficientfilm thickness, with the resistance therefore becoming large. Further,insulation films having lows dielectric constants have a likelihood todevelop problems relating to film quality, such as resistance to heatand permeability, and manufacturing problems such as dimensional changesdue to etching. For example, although dependent upon the etchingconditions, the hole diameter may become larger to approximately 1 μmfor a case in which a 1 μm thick acrylic is used, and there may bedamage in improving the overall level of integration of thesemiconductor device.

In addition, there is a method in which the formation order of theconductive layers used for forming the wirings is changed. For a casestructuring integrated circuits, having two layers of wirings for makingthe conductive connection between elements, by top gate transistors, thefollowing order of formation is normally used: active layer; firstinsulation film (gate insulation film); first conductive layer (gateelectrode); second insulation film (first interlayer insulating film);second conductive layer (first wiring); third insulation film (secondinterlayer insulating film); and third conductive layer (second wiring).

If the structure is changed to the following: first conductive layer(second wiring); first insulation film (lower portion insulation film);active layer; second insulation film (gate insulation film); secondconductive layer (gate electrode); third insulation film (firstinterlayer insulating film); and third conductive layer (first wiring);then the distance between the first wiring and the second wiring becomeslarge, and the parasitic capacitance generating between the wirings canbe reduced.

The distance between the first wiring and the second wiring becomeslarge in this case, and problems relating to openings and the conductiveconnection can be prevented through the active layer, for example.However, even with the same second wiring, with the latter case amaterial able to withstand the film formation temperature of thesubsequently formed active layer and the thermal activation temperatureof injected impurities must be used, and the same materials cannotalways be used by the former and latter cases. For example, Al is oftenused as a wiring material having a low resistivity, but its resistanceto heat is low, and it cannot be used in the latter case.

Note that, within this specification, an electrode is a portion of awiring, and the terms wiring and electrode are used separately forconvenience. However, the term wiring is always contained within theword electrode.

Semiconductor devices like those stated above are recently being used inportable devices and the like, and there are demands to make theportable devices thinner, lighter, and more flexible (flexibleproperty). The major portion of the thickness of a semiconductor deviceis the thickness of its substrate, and the substrate may be made thinnerin order to make the portable device thinner and lighter. However, ifthe substrate is made thinner, then manufacturing becomes difficult dueto trouble in photolithography processes caused by warping of thesubstrate during, manufacture, and substrate breakage more easilyoccurring during transportation of the substrate. A light, flexibledisplay device can be manufactured, provided that a semiconductor devicecan be manufactured on a transparent plastic substrate or the like, butthis has not yet been accomplished due to problems such as the heatresistance of plastic substrates.

Further, high speed operation of electric circuits and accuratepropagation of electric signals can be performed for reducing theparasitic capacitance which is generated between wirings formed ondifferent layers through an insulation film, thereby being able to usewiring materials having a low thermal resistance, such as Al, which havenot been able to be used.

SUMMARY OF THE INVENTION

The inventors of the present invention considered a method ofmanufacturing a thin film device on a substrate possessing sufficientresistance to heat and strength during manufacturing, and then removingthe substrate. First, a thin film device is formed on a first substrate,and then a second substrate is bonded. In this state, the thin filmdevice exists between the first substrate and the second substrate. Thefirst substrate is then removed, leaving the thin film device retainedon the second substrate. An opening portion for reaching the thin filmdevice retained on the second substrate is formed, and necessaryprocessing such as forming a conductive layer so as to contact the thinfilm device through the opening portion, is performed, and the secondsubstrate is also removed.

In addition, in the present invention, the first substrate and thesecond substrate are bonded by coating an adhesive in a portion ofregions in which the thin film device is not formed. Alternatively, anadhesive is applied to a portion of the regions in which the thin filmdevice is not formed, and other portions are temporarily restrainedusing a material such as viscous adhesive material. The second substratecan thus easily be removed by cutting the bonded portions.

The thin film device is always retained on one of the substrates if theabove method of manufacture is used, but both substrates are peeled offin the end, so the first substrate and the second substrate may bethick, and substrates having sufficient strength can be used. Inaddition, little substrate warping and substrate breakage develops,resulting in that the manufacture is easy.

Flaws to the back surface of the substrate during substratetransportation in display devices such as active matrix liquid crystaldisplay devices and active matrix EL display devices are a cause of adrop in display product quality, and this becomes a problem. Thesubstrates used for support during manufacture are removed if the abovemethod of manufacture is used, and therefore this problem is alsoresolved.

In addition, output electrodes can be formed in both the obverse andreverse sides of the thin film device if the above method of manufactureis used. If these are overlapped, then they can be applied to a threedimensional package and the like.

Further, there is also another invention in which a second wiring isformed in the side opposite to a first wiring with respect to an activelayer, after forming: an active layer; a first insulation film (gateinsulation film); a first conductive layer (gate electrode); a secondinsulation film (first interlayer insulating film); and a secondconductive layer (first wiring), in order. Namely, a structure to berealized in which; a first conductive layer (second wiring); a firstinsulation film (lower portion insulation film); an active layer; asecond insulation film (gate insulation film); a second conductive layer(gate electrode); a third insulation film (first interlayer insulatingfilm); and a third conductive layer (first wiring) are formed. Notethat, in this specification, the term active layer indicates a layercomposed of a semiconductor film containing a channel region, a sourceregion, and a drain region.

Parasitic capacitance generated between the first wiring and the secondwiring can be reduced by the above structure, and the wirings are formedafter forming the active layer. A material having a low resistance toheat can therefore be used.

Two substrates are used in the present invention in order to realizethis type of structure. A thin film device is formed on the firstsubstrate, and the second substrate is bonded to the surface on whichthe thin film device is formed. The first substrate is removed using amethod such as mechanical grinding or chemical grinding, with the thinfilm device supported on the second substrate. The back surface of thethin film device is exposed when the first substrate is removed, andtherefore wirings are formed. Wirings can therefore be formed on the topand bottom sides of the active layer. Cases in which transistors areformed on the first substrate, cases in which bottom gate transistorsare formed, and cases in which top gate transistors are formed can besimilarly structured. Note that the term bottom gate thin filmtransistor indicates a thin film transistor in which an active layer isformed in a layer between a gate electrode and a wiring, as shown inFIG. 27, in this specification.

Furthermore, by forming a top gate transistor on the first substrate,and then forming wirings only on the bottom side of the active layer, atransistor which becomes a bottom gate structure can be structured afterremoving the first substrate, provided that the manufacturing method ofthe present invention. In this case, parasitic capacitance between afirst wiring formed on the bottom side of the active layer and a gatewiring can be reduced. In addition, impurities can be injected in aself-aligning manner using a gate electrode though it was not possiblewith a conventional bottom gate structure.

In accordance with one aspect of the present invention, the method formanufacturing a semiconductor device comprises the steps of:

-   -   forming a thin film device on a first substrate;    -   bonding a second substrate to the surface of the first substrate        on which the thin film device is formed;    -   removing the first substrate, leaving the thin film device on        the second substrate;    -   forming an opening portion for reaching the thin film device        retained on the second substrate; and    -   cutting the second substrate so that the bonding portion of thin        film device and the second substrate is removed, and removing        the second substrate.

In accordance with another aspect of the present invention, the methodfor manufacturing a semiconductor device comprises the steps of:

-   -   forming a thin film device on a first substrate;    -   bonding a second substrate to the surface of the first substrate        on which the thin film device is formed;    -   removing the first substrate, leaving the thin film device on        the second substrate;    -   forming an opening portion for reaching the thin film device        retained on the second substrate, and forming at lest one        conductive layer contacting the thin film device through the        opening portion; and    -   cutting the second substrate so that the bonding portion of the        thin film device and the second substrate is removed, and        removing the second substrate.

In accordance with another aspect of the present invention, the methodfor manufacturing a semiconductor device comprises the steps of:

-   -   forming a thin film device on a first substrate;    -   coating regions in which the thin film device is formed, and        regions in which the thin film device is not formed, separately        by using at least two types of adhesives, and bonding a second        substrate to the surface of the first substrate on which the        thin film device is formed;    -   removing the first substrate, leaving the thin film device on        the second substrate;    -   forming an opening portion for reaching the thin film device        retained on the second substrate; and    -   cutting the second substrate so that the regions coated with        adhesive are removed.

In accordance with another aspect of the present invention, the methodfor manufacturing a semiconductor device comprises the steps of:

-   -   coating regions in which the thin film device is formed, and        regions in which the thin film device is not formed, separately        by using at least two types of adhesives, and bonding a second        substrate to the thin film device formed on the first substrate;    -   removing the first substrate, leaving the thin film device on        the second substrate;    -   forming an opening portion for reaching the thin film device        retained on the second substrate, and forming at least one        conductive layer contacting the thin film device through the        opening portion; and    -   cutting the second substrate so that the regions coated with        adhesive are removed.

In accordance with another aspect of the present invention, the methodfor manufacturing a semiconductor device comprises the steps of:

-   -   forming a first thin film device on one surface of a first        substrate;    -   partially bonding a thin film or a second thin film device to a        second substrate;    -   bonding the thin film or the second thin film device bonded to        the second substrate to the first thin film device formed on the        first substrate;    -   removing the first substrate, leaning the first thin film device        on the second substrate;    -   forming an opening portion in the first thin film device        retained on the second substrate; and    -   cutting the second substrate so that the bonding portion of the        thin film, or the second thin film device, and the second        substrate is removed, and removing only the second substrate,        leaving the thin film or the second thin film device.

In accordance with another aspect of the present invention, the methodfor manufacturing a semiconductor device comprises the steps of:

-   -   forming a first thin film device on one surface of a first        substrate;    -   partially bonding a thin film or a second thin film device to a        second substrate;    -   bonding the thin film or the second thin film device bonded to        the second substrate to the first thin film device formed on the        first substrate;    -   removing the first substrate, leaving the thin film device on        the second substrate;    -   forming at least one conductive layer on the first thin film        device retained on the second substrate; and    -   cutting the second substrate so that the bonding portion of the        thin film, or the second thin film device, and the second        substrate is removed, and removing only the second substrate,        leaving the thin film or the second thin film device.

In accordance with another aspect of the present invention, the methodfor manufacturing a semiconductor device comprises the steps of:

-   -   forming a first thin film device on one surface of a first        substrate;    -   coating locations in which the thin film device exists, and        locations in which the thin film device does not exist,        separately by using at least two types of adhesives, and bonding        a thin film or a second thin film device to a second substrate;    -   bonding the thin film or the second thin film device bonded to        the second substrate to the first thin film device formed on the        first substrate;    -   removing the first substrate, leaving the thin film device on        the second substrate;    -   forming an opening portion in the first thin film device        retained on the second substrate; and    -   cutting the second substrate so that a portion of the thin film,        or the second thin film device, and the second substrate is        removed. Land removing only the second substrate, leaving the        thin film or the second thin film device.

In accordance with another aspect of the present invention, the methodfor manufacturing a semiconductor device comprises the steps of:

-   -   forming a first thin film device on one surface of a first        substrate;    -   coating locations in which the thin film device exists, and        locations in which the thin film device does not exist,        separately by using at least two types of adhesives, and bonding        a thin film or a second thin film device to a second substrate;    -   bonding the thin film or the second thin film device bonded to        the second substrate to the first thin film device formed on the        first substrate;    -   removing the first substrate, leaving the first thin film device        on the second substrate;    -   forming at least one conductive layer in the first thin film        device retained on the second substrate; and    -   cutting the second substrate so that a portion of the thin film,        or the second thin film device, and the second substrate is        removed, and removing only the second substrate, leaving the        thin film or the second thin film device.

In accordance with another aspect of the present invention, the methodfor manufacturing a semiconductor device comprises the steps of:

-   -   forming a first thin film device on one surface of a first        substrate;    -   partially bonding a thin film or a second thin film device to a        second substrate;    -   bonding the thin film or the second thin film device bonded to        the second substrate to the first thin film device formed on the        first substrate; and    -   cutting the second substrate so that the bonding portion of the        thin film, or the second thin film device, and the second        substrate is removed, and removing only the second substrate,        leaving the thin film or the second thin film device.

In accordance with another aspect of the present invention, the methodfor manufacturing a semiconductor device comprises the steps of:

-   -   forming a first thin film device on one surface of a first        substrate;    -   coating locations in which the thin film device exists, and        locations in which the thin film device does not exist,        separately by using at least two types of adhesives, and bonding        a thin film or a second thin film device to a second substrate;    -   bonding the thin film or the second thin film device bonded to        the second substrate to the first thin film device formed on the        first substrate; and    -   cutting the second substrate so that a portion of the thin film,        or the second thin film device, and the second substrate is        removed, and removing only the second substrate, leaving the        thin film or the second thin film device.

In accordance with another aspect of the present invention, the methodfor manufacturing a semiconductor device comprises the steps of:

-   -   forming a first thin film device on one surface of a first        substrate;    -   partially bonding a thin film or a second thin film device to a        second substrate;    -   introducing liquid crystals between the first thin film device        formed on the first substrate and the thin film, or the second        thin film device, bonded to the second substrate; and    -   cutting the first substrate, the first thin film device, the        second substrate, and the thin film or the second thin film        device, so that a portion of the first substrate, the first thin        film device, the second substrate, and the thin film or the        second thin film device is removed, and removing the second        substrate, leaving the thin film or the second thin film device.

In accordance with another aspect of the present invention, the methodfor manufacturing a semiconductor device comprises the steps of:

-   -   forming a first thin film device on one surface of a first        substrate;    -   coating locations in which the thin film device exists, and        locations in which the thin film device does not exist,        separately by using at least two types of adhesives, and bonding        a thin film or a second thin film device to a second substrate;    -   introducing a liquid crystal between the first thin film device        formed on the first substrate and the thin film, or the second        thin film device, bonded to the second substrate; and    -   cutting the first substrate, the first thin film device, the        second substrate, and the thin film or the second thin film        device, so that a portion of the first substrate, the first thin        film device, the second substrate, and the thin film or the        second thin film device is removed, and removing the second        substrate, leaving the thin film or the second thin film device.

In accordance with another aspect of the present invention, the methodfor manufacturing a semiconductor device comprises the steps of:

-   -   forming a thin film device on one face of a first substrate;    -   partially bonding a polarization film or a polarization plate to        a second substrate;    -   bonding the polarization film or the polarization plate bonded        to the second substrate to the thin film device formed on the        first substrate;    -   removing the first substrate, leaving the thin film device on        the second substrate;    -   forming an opening portion in the thin film device retained on        the second substrate; and    -   cutting the second substrate so that the bonding portion of the        polarization film, or the polarization plate, and the second        substrate is removed, and removing only the second substrate,        leaving the polarization film or the polarization plate.

In accordance with another aspect of the present invention, the methodfor manufacturing a semiconductor device comprises the steps of:

-   -   forming a thin film device on one face of a first substrate;    -   partially bonding a polarization film or a polarization plate to        a second substrate;    -   bonding the polarization film or the polarization plate bonded        to the second substrate to the thin film device formed on the        first substrate;    -   removing the first substrate, leaving the thin film device on        the second substrate;    -   forming at least one conductive layer on the thin film device        retained on the second substrate; and    -   cutting the second substrate so that the bonding portion of the        polarization film, or the polarization plate, and the second        substrate is removed, and removing only the second substrate,        leaving the polarization film or the polarization plate.

In accordance with another aspect of the present invention, the methodfor manufacturing a semiconductor device comprises the steps of:

-   -   forming a thin film device on one face of a first substrate;    -   coating locations in which the thin film device exists, and        locations in which the thin film device does not exist,        separately by using at least two types of adhesives, and bonding        a polarization film or a polarization plate to a second        substrate;    -   bonding the polarization film or the polarization plate bonded        to the second substrate to the thin film device formed on the        first substrate;    -   removing the first substrate, leaving the thin film device on        the second substrate;    -   forming an opening portion in the thin film device retained on        the second substrate; and    -   cutting the second substrate so that a portion of the        polarization film, or the polarization plate, and the second        substrate is removed, and removing only the second substrate,        leaving the polarization film or the polarization plate.

In accordance with another aspect of the present invention, the methodfor manufacturing a semiconductor device comprises the steps of:

-   -   forming a thin film device on one face of a first substrate;    -   coating locations in which the thin film den ice exists, and        locations in which the thin film device does not exist,        separately by using at least two types of adhesives, and bonding        a polarization film or a polarization plate to a second        substrate;    -   bonding the polarization film or the polarization plate bonded        to the second substrate to the thin film device formed on the        first substrate;    -   removing the first substrate, leaving the thin film device on        the second substrate;    -   forming at least one conductive layer on the thin film device        retained on the second substrate; and    -   cutting the second substrate so that a portion of the        polarization film, or the polarization plate, and the second        substrate is removed, and removing only the second substrate,        leaving the polarization film or the polarization plate.

In accordance with another aspect of the present invention, the methodfor manufacturing a semiconductor device comprises the steps of:

-   -   forming a thin film device on one surface of a first substrate;    -   forming an electrode on the thin film device;    -   partially bonding a second substrate to the thin film device        formed on the first substrate, and;    -   removing the first substrate, leaving the thin film device oil        the second substrate;    -   forming an opening portion in the thin film device retained on        the second substrate;    -   cutting the second substrate so that the bonding portion of the        thin film device and the second substrate is removed, and        removing the second substrate; and    -   forming and overlapping a plurality of thin film devices from        the thin film device obtained in accordance with the preceding        steps, and making the electrodes formed on the top and an        electrode formed on the bottom of the thin film devices        conductive.

In accordance with another aspect of the present invention, the methodfor manufacturing a semiconductor device comprises the steps of:

-   -   forming a thin film device on one surface of a first substrate;    -   forming an electrode on the thin film device;    -   partially bonding a second substrate to the thin film device        formed on the first substrate;    -   removing the first substrate, leaving the thin film device on        the second substrate;    -   forming an opening portion in the thin film device retained on        the second substrate, and forming at least one conductive layer        to form an electrode;    -   cutting the second substrate so that the bonding portion of the        thin film device and the second substrate is removed, and        removing the second substrate; and    -   forming and overlapping a plurality of thin film devices from        the thin film device obtained in accordance with the preceding        steps, and making the electrodes formed on the top and bottom of        the thin film devices conductive.

In accordance with another aspect of the present invention, the methodfor manufacturing a semiconductor device comprises the steps of:

-   -   forming a thin film device on one surface of a first substrate;    -   forming an electrode on the thin film device;    -   coating locations in which the thin film device exists, and        locations in which the thin film device does not exist,        separately by using at least two types of adhesives, and bonding        a second substrate to the thin film device formed on the first        substrate;    -   removing the first substrate, leaving the thin film device on        the second substrate;    -   forming an opening portion in the thin film device retained on        the second substrate;    -   cutting the second substrate so that a portion of the thin film        device and the second substrate is removed, and removing the        second substrate; and    -   forming and overlapping a plurality of thin film devices from        the thin film device obtained in accordance with the preceding        steps, and making the electrodes formed on the top and an        electrode formed on the bottom of the thin film devices        conductive.

In accordance with another aspect of the present invention, the methodfor manufacturing a semiconductor device comprises the steps of:

-   -   forming a thin film device on one surface of a first substrate;    -   forming an electrode on the thin film device;    -   coating locations in which the thin film device exists, and        locations in which the thin film device does not exist,        separately by using at least two types of adhesives, and bonding        a second substrate to the thin film device formed on the first        substrate;    -   removing the first substrate, leaving the thin film device on        the second substrate;    -   forming an opening portion in the thin film device retained on        the second substrate, and forming at least one conductive layer,        forming an electrode;    -   cutting the second substrate so that the bonding portion of the        thin film device and the second substrate is removed, and        removing the second substrate; and    -   forming and overlapping a plurality of thin film devices from        the thin film device obtained in accordance with the preceding        steps, and making the electrodes formed on the top and bottom of        the thin film devices conductive.

In accordance with another aspect of the present invention, the methodfor manufacturing a semiconductor device comprises the steps of:

-   -   forming a first thin film device on one surface of a first        substrate;    -   forming an electrode on the first thin film device;    -   partially bonding a thin film or a second thin film device        having an opening portion to a second substrate; or forming an        opening portion in the thin film or the second thin film device        after partially bonding the thin film or the second thin film        device to the second substrate;    -   bonding the thin film or the second thin film device bonded to        the second substrate to the first thin film device formed on the        first substrate;    -   removing the first substrate, leaving the first thin film device        on the second substrate;    -   forming an opening portion in the first thin film device        retained on the second substrate;    -   cutting the second substrate so that the bonding portion of the        thin film, or the second thin film device, and the second        substrate is removed, and removing only the second substrate,        leaving the thin film or the second thin film device; and    -   forming and overlapping a plurality of thin film devices from        the thin film device obtained in accordance with the preceding        steps, and making the electrodes formed on the top and bottom of        the thin film devices conductive.

In accordance with another aspect of the present invention, the methodfor manufacturing a semiconductor device comprises the steps of:

-   -   forming a first thin film device on one surface of a first        substrate;    -   forming an electrode on the first thin film device;    -   partially bonding a thin film, or a second thin film device,        having an opening portion, to a second substrate; or forming an        opening portion in the thin film or the second thin film device        after partially bonding, the thin film or the second thin film        device to the second substrate;    -   bonding the thin film or the second thin film device bonded to        the second substrate to the first thin film device formed on the        first substrate;    -   removing the first substrate, leaving the first thin film device        on the second substrate;    -   forming an opening portion in the first thin film device        retained on the second substrate, and forming at least one        conductive layer to form an electrode;    -   cutting the second substrate so that the bonding portion of the        thin film, or the second thin film device, and the second        substrate is removed, and removing only the second substrate,        leaving the thin film or the second thin film device; and    -   forming and overlapping a plurality of thin film devices from        the thin film device obtained in accordance with the preceding        steps, and making the electrodes formed on the top and bottom of        the thin film devices conductive.

In accordance with another aspect of the present invention, the methodfor manufacturing a semiconductor device comprises the steps of:

-   -   forming a first thin film device on one surface of a first        substrate;    -   forming an electrode on the first thin film device;    -   coating locations in which the thin film device exists, and        locations in which the thin film device does not exist,        separately by using at least two types of adhesives, and bonding        a thin film, or a second thin film device, having an opening        portion, to a second substrate; or coating locations in which        the thin film device exists, and locations in which the thin        film device does not exist, separately by using at least tango        types of adhesives to form an opening portion in the thin film        or the second thin film device after bonding the thin film or        the second thin film device to the second substrate;    -   bonding the thin film or the second thin film device bonded to        the second substrate to the first thin film device formed on the        first substrate;    -   removing the first substrate, leaving the first thin film device        on the second substrate;    -   forming an opening portion in the first thin film device        retained on the second substrate;    -   cutting the second substrate so that a portion of the thin film,        or the second thin film device, and the second substrate is        removed, and removing only the second substrate, leaving the        thin film or the second thin film device; and    -   forming and overlapping a plurality of thin film devices from        the thin film device obtained in accordance with the preceding        steps, and making the electrodes formed on the top and bottom of        the thin film devices conductive.

In accordance with another aspect of the present invention, the methodfor manufacturing a semiconductor device comprises the steps of:

-   -   forming a first thin film device on one surface of a first        substrate;    -   forming an electrode on the first thin film device;    -   coating locations in which the thin film device exists, and        locations in which the thin film device does not exist,        separately by using at least two types of adhesives, and bonding        a thin film, or a second thin film device, having an opening        portion, to a second substrate; or coating locations in which        the thin film device exists, and locations in which the thin        film device does not exist, separately by using at least two        types of adhesives to form an opening portion in the thin film        or the second thin film device after bonding the thin film or        the second thin film device to the second substrate;    -   bonding the thin film or the second thin film device bonded to        the second substrate to the first thin film device formed on the        first substrate;    -   removing the first substrate, leaving the first thin film device        oil the second substrate;    -   forming an opening portion in the first thin film device        retained on the second substrate, and forming at least one        conductive layer to form an electrode;    -   cutting the second substrate so that a portion of the thin film,        or the second thin film device, and the second substrate is        removed, and removing only the second substrate, leaving the        thin film or the second thin film device; and    -   forming and overlapping a plurality of thin film devices from        the thin film device obtained in accordance with the preceding        steps, and making the electrodes formed on the top and bottom of        the thin film devices conductive.

In accordance with another aspect of the present invention, the methodfor manufacturing a semiconductor device comprises the steps of:

-   -   forming a thin film device on a first substrate;    -   bonding the surface of the first substrate on which the thin        film device is formed to a second substrate;    -   removing the first substrate; and    -   forming an opening portion in the thin film device retained on        the second substrate.

In accordance with another aspect of the present invention, the methodfor manufacturing a semiconductor device comprises the steps of:

-   -   forming a thin film device on a first substrate;    -   bonding the surface of the first substrate on which the thin        film device is formed to a second substrate;    -   removing the first substrate; and    -   forming at least one conductive layer in the thin film device        retained on the second substrate.

In accordance with another aspect of the present invention, thesemiconductor device comprises a semiconductor formed on an insulator asan active layer, wherein: at least one conductive layer is formed above,and below, the active layer using a material capable of withstanding atemperature of 550° C.

In accordance with another aspect of the present invention, the thinfilm transistor comprises a semiconductor formed on an insulator as anactive layer, comprising:

-   -   a gate insulating film on the active layer;    -   a gate electrode on the gate insulating film;    -   performing impurity addition using the gate electrode as a mask;        and    -   a wiring on the side opposite the gate electrode, with respect        to the active layer, using a material having a resistance to        heal equal to or less than 550° C.

In accordance with another aspect of the present invention, thesemiconductor device comprises a semiconductor formed on an insulator asan active layer, comprising:

-   -   a pair of polarization films;    -   a pixel electrode;    -   a thin film transistor composed of: an active layer; a gate        insulating film contacting the active layer; and a gate        electrode contacting the gate insulating film;    -   a wiring connected to the active layer from the gate electrode        side;    -   an opposing electrode;    -   liquid crystals between a pixel electrode formed between the        pair of polarization films, and the opposing electrode;    -   a sealant; and    -   an orientation film.

In accordance with another aspect of the present invention, thesemiconductor device comprises a semiconductor formed on an insulator asan active layer comprising:

-   -   a pair of polarization films;    -   a thin film transistor composed of: an active layer contacting a        first insulating film; a gate insulating film contacting the        active layer; and a gate electrode contacting the gate        insulating film;    -   a third insulating film contacting the gate electrode;    -   a passivation film contacting the third insulating film;    -   a wiring electrically connected to each thin film transistor        through an opening portion formed in the third insulating film        and in the gate insulating film;    -   a pixel electrode formed in the surface opposite that in which        the gate electrode of the active layer is formed;    -   an orientation film formed contacting the pixel electrode;    -   an opposing electrode formed in one polarization film of the        pair of polarizing films;    -   liquid crystals between the pixel electrode, formed between the        pair of polarizing films, and the opposing electrode; and    -   a sealant formed between the first insulating film and the pair        of polarizing films.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings:

FIGS. 1A to 1D are diagrams showing an embodiment mode of the presentinvention;

FIGS. 2A and 2B are diagrams showing an embodiment mode of the presentinvention;

FIGS. 3A to 3C are diagrams showing an embodiment mode of the presentinvention;

FIGS. 4A and 4B are diagrams showing an embodiment mode of the presentinvention;

FIGS. 5A and 5B are diagrams showing an embodiment mode of the presentinvention;

FIG. 6 is a diagram showing an embodiment mode of the present invention;

FIGS. 7A to 7F are diagrams showing an example of an embodiment of thepresent invention;

FIGS. 8A to 8D are diagrams showing an example of an embodiment of thepresent invention;

FIGS. 9A to 9D are diagrams showing an example of all embodiment of thepresent invention;

FIGS. 10A to 10C are diagrams showing an example of an embodiment of thepresent invention;

FIGS. 11A and 11B are diagrams showing an examples of all embodiment ofthe present invention;

FIG. 12 is a diagram showing an example of an embodiment of the presentinvention;

FIG. 13 is a diagram showing an example of an embodiment of the presentinvention;

FIGS. 14A to 14C are diagrams showing an example of an embodiment of thepresent invention;

FIGS. 15A and 15B are diagrams showing an example of an embodiment ofthe resent invention;

FIG. 16 is a diagram showing an example of an embodiment of the presentinvention;

FIGS. 17A to 17E are diagrams showing an example of an embodiment of thepresent invention;

FIGS. 18A to 18D are diagrams showing an example of an embodiment of thepresent invention;

FIGS. 19A to 19D are diagrams showing an example of an embodiment of thepresent invention;

FIGS. 20A to 20C are diagrams showing an example of an embodiment of thepresent invention;

FIG. 21 is a diagram shorting an example of an embodiment of the presentinvention;

FIG. 22 is a diagram showing an example of an embodiment of the presentinvention;

FIG. 23 is a diagram showing an example of an embodiment of the presentinvention;

FIGS. 24A to 24C are diagrams showing an active matrix EL display devicemanufactured using the present invention;

FIG. 25 is a diagram showing an active matrix EL display devicemanufactured using the present invention;

FIG. 26 is a diagram showing an active matrix EL display devicemanufactured using the present invention;

FIG. 27 is a diagram showing an example of an embodiment of the presentinvention; and

FIGS. 28A to 28F are diagrams showing examples of electronic devices.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment Mode 1

A method of manufacturing an active matrix liquid crystal display deviceusing the present invention is explained using FIG. 1A to FIG. 3C.

First, a thin film device (which becomes a thin film device 103) ismanufactured on a TFT formation substrate 101 as a first substrate. Aleveling film 103 may be added, leveling a surface for bonding a secondsubstrate. (See FIG. 1A.)

A supporting material 104 is prepared as a second substrate, and apolarization film 107 is attached by an adhesive. Note that an exampleof bonding in which two types of adhesives are used separately is shownhere. An adhesive A 105 bonds the outside of the thin film device 102when joining the first substrate and the second substrate, as stated thebelow, and an adhesive B 106 is a viscous adhesive and temporarilyrestrains the polarization film during a period up until the supportingmaterial 104 is removed. (See FIG. 1B.)

A polarization film may also be joined to the leveling film 103 over theTFT formation substrate 101, of course, and be bonded to the supportingmaterial 104 bonded.

In FIG. 1C, an adhesive is coated on the fringe of the leveling film 103formed over the TFT formation substrate 101 through the thin film device102, and on the fringe of the surface of the supporting material 104 onwhich the polarization film 107 is attached, and both substrates arebonded. The first substrate is then removed by a method such as backgrinding or CMP, thereby exposing the surface of the thin film device102. (See FIG. 1D.) In practice, a film such as a nitride film may alsobe prepared as a stopper in the lowest layer of the thin film device102, and wet etching performed at the end of grinding.

A pixel electrode 108 is formed next in the thin film device 102retained on the supporting material 104. (See FIG. 2A.) An opposingelectrode 110 is attached to the polarization film 112, and liquidcrystals 109 are enclosed using a sealant 111. (See FIG. 2B.) Note thatone more supporting material may be prepared to support the polarizationfilm 112 in case the polarization film flexes.

In FIG. 3A, the substrate is cut at locations for detaching the adhesiveA 105 in the outside of the thin film device 102. Regions coated by theadhesive A 105 are removed by cutting, thereby only leaving regionscoated by the viscous adhesive as the adhesive B106 (see FIG. 3B), andthe supporting material 104 is removed. (See FIG. 3C.)

A semiconductor device can thus be given flexibility (flexibleproperty), made thinner, and made lighter weight by manufacturing in astate in which it is fixed to a substrate, and by lastly removing thesubstrate. Note that an example relating to an active matrix liquidcrystal display device is shown here, and therefore the polarizationfilm is joined to the surface after removal from the substrate.Depending upon the usage objective, a film for surface protection, afilm as a supporting material, and the like can freely combined andused.

Embodiment Mode 2

A manufacturing method of the present invention is explained simplyregarding a semiconductor device using a thin film transistor (TFT). Theexplanation here is made by utilizing a cross sectional diagram of onethin film transistor and wirings, but it can also be applied to anintegrated circuit using a plurality of transistors, of course.

An etching stopper 1102, which will be later utilized when removing afirst substrate 1101, is formed on the first substrate 1101. Atransistor is structured by a lower portion insulation film 1103, anactive layer 1104 composed of a semiconductor such as silicon, a gateinsulation film 1105, and a gate electrode 1106 formed on the etchingstopper 1102. A first interlayer insulating film 1107 is formed, inopening portion for reaching the active layer 1104 is formed, and afirst wiring 1108 is formed through the opening portion. A secondinterlayer insulation film 1109 is formed (See FIG. 4A.)

A second substrate 1110 is bonded to the surface of the side of thefirst substrate 1101 over which a thin film device is formed, the firstsubstrate 1101 and the etching stopper 1102 are removed, and an openingportion for reaching the active layer 1104 is formed. (See FIG. 4B.) Itis not always necessary to form the etching stopper 1102, but a filmsuch as a nitride film may be prepared in the lowest layer of thetransistor and used as a stopper by performing wet etching last.

A second wiring 1111 contacting the active layer through the openingportion is formed, and an insulation film 1112 is formed. (See FIG. 5A.)The conductive connection is formed between the first wiring 1108 andthe second wiring 1111 through the active layer in this case, but alarger opening portion may also be formed in only a portion foralignment precision, and the two wirings may be connected directly.Whichever method is used, opening portions are formed from the top andthe bottom with the structure of the present invention, and therefore itis easy to form the conductive connection. Further, wirings are formedafter forming the active layer, and therefore wirings having low heatresistance can be used.

An active layer, a gate insulating film, a gate electrode, a firstinterlayer insulating film, a first wiring, a second interlayerinsulating film, a second wiring, and the second wiring for aconventional structure are shown at the same time in FIG. 6 forcomparison. Note that first wirings 1151 and 1154, and second wirings1155 and 115 are cross sections of wirings which are not electricallyconnected to the thin film transistor shown in the figures here.

If the structure of the present invention is not used, a second wiring1158 is in a location denoted by reference numeral 1156, the secondwiring 1156 is close to the first wiring 1154, and their parasiticcapacitance also becomes large. Further, the second wiring 1157 may beformed in the location denoted by reference numeral 1155, or may beformed in the location denoted by reference numeral 1115 as a firstwiring. In this case, the distance to a first wiring 1152 becomes short.

In other words, the distance between the first wirings and the secondwirings is the thickness of the second interlayer insulating film withthe conventional structure, and it becomes the combined thickness of thelower portion insulation film and the first interlayer insulating filmwith the manufacturing method of the present invention. The combinedthickness of the lower portion insulation film and the first interlayerinsulating film of course is larger than the thickness of the secondinterlayer insulating film.

The effective thickness of the insulation films between the wirings canthus be increased, and the parasitic capacitance which is generatedbetween wirings formed in different layers can be reduced, by using themanufacturing method of the present invention. Note that, although thereare problems in the conductive connection through the insulation filmsby simply making the insulation films thicker, as done conventionally,there are no such problems with the method of manufacture of the presentinvention. Further, the structure in which wirings are formed inportions belong the active layer are the same as with conventionalstructures, but the wirings are formed after forming the active layer,and therefore wiring materials having low heat resistance can be used.Low resistance wirings which could not be used due to their lows thermalresistance can therefore be used.

EMBODIMENTS Embodiment 1

An example of applying a method of manufacturing a semiconductor deviceof the present invention to an active matrix liquid crystal displaydevice is shown here. Note that only one pixel portion of a liquidcrystal display device is shown in the figures because locations atwhich adhesives are used separately, sealant locations, locations forcutting substrates, and the like are explained. The present inventioncan be applied, of course, to devices such as a liquid crystal displaydevice having a plurality of pixels, and to a liquid crystal displaydevice formed integrated with a driver circuit.

A glass substrate or a quartz substrate can be used as a first substrate400 in FIG. 7A. In addition, substrates having an insulation film formedon their surfaces, such as a silicon substrate, a metallic substrate, ora stainless steel substrate, can also be used.

An etching stopper 401 is formed next for removal of the first substrate400. A material having a selectivity which is sufficiently large withrespect to the first substrate is used for the etching stopper 401. Aquartz substrate is used as the first substrate 400, and a siliconnitride film having a thickness of 10 to 1000 nm (typically between 100and 500 nm) is formed on the etching stopper 401 in this embodiment.

A first insulation film 402 is formed on the etching stopper 401 from a10 to 1000 nm thick (typically 300 to 500 nm thick) silicon oxide film.Further, a silicon oxynitride film may also be used.

Subsequently, a 10 to 100 nm thick amorphous semiconductor film (anamorphous silicon film 403 in this embodiment) is formed by a known filmformation method on the first insulation film 402. Note that, inaddition to the amorphous silicon film, an amorphous compoundsemiconductor film such as amorphous silicon germanium film can also beused as the amorphous semiconductor film.

A semiconductor film containing a crystalline structure (a crystallinesilicon film 404 in this embodiment) is then formed in accordance withthe technique recorded in Japanese Patent Application Laid-open No.7-130652 (U.S. Pat. No. 5,643,826). The technique recorded in the abovepatent is a means of crystallization using a catalyst element (oneelement, or a plurality of elements, selected from the group consistingof nickel, cobalt, germanium, tin, lead, palladium, iron, and copper,typically nickel) for promoting crystallization when crystallizing anamorphous silicon film.

Specifically, heat treatment is performed in a state in which thecatalyst element is retained in the surface of the amorphous siliconfilm, thereby chancing the amorphous silicon film to a crystallinesilicon film. The technique recorded in Embodiment 1 of the above patentis used in this embodiment of the present invention, but the techniquerecorded in Embodiment 2 of the patent may also be used. Note thatsingle crystalline silicon films and polycrystalline silicon films arecontained with the term crystalline silicon film, and that thecrystalline silicon film formed in this embodiment is a silicon filmhaving crystal boundaries.

Although depending upon the amount of hydrogen contained in theamorphous silicon film, it is preferable to perform dehydrogenationprocessing be heat treatment at 400 to 550° C. for several hours,thereby reducing the amount of contained hydrogen to 5 atomic % or less,and then performing crystallization. Further, other method ofmanufacturing the amorphous silicon film, such as sputtering orevaporation, may also be used: however, it is preferable to sufficientlyreduce impurity elements such as oxygen and nitrogen contained withinthe film.

A known technique may be used on the amorphous silicon film 403 to formthe crystalline silicon film (polysilicon film or polycrystallinesilicon film) 404. Light emitted from a laser (hereafter referred to aslaser light) is irradiated to the amorphous silicon film 403 in thisembodiment to form the crystalline silicon film 404. (See FIG. 7C.) Apulse emission type or continuous emission type excimer laser may beused as the laser, and a continuous emission argon laser may also beused. Alternatively, the second harmonic, the third harmonic, or thefourth harmonic of an Nd:YAG laser or an Nd:YVO laser may also be used.In addition, the beam shape of the laser light may be a linear shape(including long and thin shapes) or a rectangular shape.

Furthermore, light emitted from a lamp (hereafter referred to as lamplight) may also be irradiated as a substitute for the laser light(hereafter referred to as lamp annealing). Lamp light emitted from alamp such as a halogen lamp or an infrared lamp can be used as the lamplight.

A process of performing thermal processing (annealing) as above by laserlight or lamp light is referred to as an optical annealing process. Theoptical annealing process is performed at a high processing temperaturefor a short time, and therefore the thermal process can be performedeffectively and at high throughput for cases in which a substrate havinglow resistance to heat, such as a glass substrate, is used. Of course,the aim is to perform annealing, and therefore furnace annealing(thermal annealing) can also be performed by using an electric furnaceas a substitute.

Laser annealing is performed in this embodiment using light from a pulseemission excimer laser formed into a linear shape. The laser annealingconditions are as follows: XeCl gas is used as an excitation gas; theprocessing temperature is set to room temperature; the pulse emissionfrequency is set to 30 Hz; and the laser energy density is from 250 to500 mJ/cm² (typically between 350 and 400 mJ/cm²).

Along with the complete crystallization of any amorphous regionsremaining after thermal crystallization, laser annealing performed atthe above conditions has an effect of lowering faults or the like in thecrystalline regions already crystallized. This process can thereforealso be referred to as a process for improving the crystallinity of thesemiconductor film by optical annealing, and a process for promotingcrystallization of the semiconductor film. It is also possible to obtainthese types of effects by optimizing the lamp annealing conditions.

A protective film 405, used during subsequent impurity addition, isformed next on the crystalline silicon film 404. (See FIG. 7D.) Theprotective film 405 is formed using a silicon oxynitride film, or asilicon oxide film, having a thickness from 100 to 200 nm (preferablybetween 130 and 1701 nm). The protective film 405 is formed so that thecrystalline silicon film 404 is not directly exposed to a plasma duringimpurity addition, and in order to make delicate temperature controlpossible.

Subsequently an impurity element which imparts p-type conductivity(hereafter referred to as a p-type impurity) is added through theprotective film 405. Typically a periodic table group 13 element,usually boron or gallium, can be used as the p-type impurity element.This process (also referred to as a channel doping process) is one forcontrolling the TFT threshold voltage. Note that boron is added here byion doping in which a plasma is excited using diborane (B₂H₆) withoutseparation of mass. Ion implantation, in which mass separation isperformed, may of course also be used.

A p-type impurity region (a) 406 containing a p-type impurity element(boron in this embodiment) at a concentration of 1×10¹⁵ to 1×10¹⁸atoms/cm³ (typically between 5×10¹⁶ and 5×10¹⁷ atoms/cm³) is formed bythis process. (See FIG. 7D.)

Next, after removing the protective film 405, unnecessary portions ofthe crystalline silicon film are removed, thereby forming anisland-shape semiconductor film (hereafter referred to as an activelayer) 407. (See FIG. 7E.)

A gate insulation film 408 is formed, covering the active lacer 407.(See FIG. 7F.) The gate insulation film 408 may be formed having athickness of 10 to 200 nm, preferably from 50 to 150 nm. A siliconoxynitride film is formed having a thickness of 80 nm by plasma CVDusing N₂O and SiH₄ as raw materials.

Although not shown in the figures, a two layer lamination film oftungsten nitride (WN) having a thickness of 50 nm and tantalum (Ta)having a thickness of 350 nm is used as a gate wiring 409. (See FIG.8A.) The gate wiring may also be formed by a single layer conductivefilm, but it is preferable to use a two layer or a three layerlamination film when necessary.

Note that an element selected from the group consisting of tantalum(Ta), titanium (Ti), molybdenum (Mo), tungsten (W), chromium (Cr), andsilicon (Si), or an alloy film of a combination of the above-mentionedelements (typically an Mo—W alloy or an Mo—Ta alloy) can be used as thegate wiring.

Next, an n-type impurity element (phosphorous in this embodiment) isadded in a self aligning manner with the gate wiring 409 as a mask. (SeeFIG. 8B.) The addition process is regulated so that phosphorous is addedto an n-type impurity region (a) 410 thus formed at a concentration(typically from 1×10¹⁶ to 5×10¹⁸ atoms/cm³, more typically between3×10¹⁷ and 3×10¹⁸ atoms/cm³) which is from 5 to 10 times higher than theboron concentration added by the channel doping process.

A resist mask 411 is formed, an n-type impurity element (phosphorous inthis embodiment) is added, and an n-type impurity region (b) 412containing a high concentration of phosphorous is formed. (See FIG. 8C.)Ion doping using phosphine (PH₃) is performed here (ion implantation mayalso be performed, of course), and the concentration of phosphorous inthis region is set from 1×10²⁰ to 1×10²¹ atoms/cm³ (typically between2×10²⁰ and 5×10²⁰ atoms/cm³).

Further, phosphorous and boron which have been added in the previousprocess are already contained in regions in which the n-type impurityregion (b) 412 is formed, but phosphorous is added at a sufficientlyhigh concentration here, and therefore one need not consider theinfluence of phosphorous and boron already added by the prior steps.

After removing the resist mask 411, a third insulation film 414 isformed. (See FIG. 8D.) An insulation film containing silicon,specifically a silicon nitride film, a silicon oxide film, a siliconoxynitride film, or a lamination film of a combination of these films,may be formed with a thickness of 600 nm to 1.5 μm as the thirdinsulation film 414. A 1 μm thick silicon oxynitride film (with anitrogen concentration from 25 to 50 atomic %) is formed in thisembodiment using plasma CVD with SiH₄, N₂O, and NH₃ as raft materialgasses.

A heat treatment process is performed next in order to activate then-type and p-type impurity elements added at their respectiveconcentration. (See FIG. 8D.) This process can be performed by furnaceannealing, laser annealing, or rapid thermal annealing (RTA). Theactivation process is performed here by furnace annealing. The heattreatment process is performed within a nitrogen atmosphere at 300 to650° C. preferably between 400 and 550° C. Heat treatment is performedhere for 4 hours at 550° C.

The catalyst element used in crystallizing the amorphous silicon film(nickel in this embodiment) moves in the direction shown by the arrow atthis point in this embodiment, and is captured (gettered) in the n-typeimpurity region (b) 412 containing a high concentration of phosphorousand which is formed by the step shown in FIG. 8C. This is a phenomenacaused by the gettering effect of metallic elements by phosphorous, andas a result, the concentration of the catalyst element in a channelregion 413 becomes less than or equal to 1×10¹⁷ atoms/cm³ (preferablyless than or equal to 1×10¹⁶ atoms cm³).

Conversely, the catalyst element is segregated in a high concentrationin a region which becomes a gettering site for the catalyst element (then-type impurity region (b) 412 formed by the step shown in FIG. 8C), andthe catalyst element exists there at a concentration greater than orequal to 5×10¹⁸ atoms cm³ (typically from 1×10¹⁹ to 5×20²⁰ atoms cm³).

In addition, heat treatment is performed at a temperature of 300 to 450°C. for 1 to 12 hours in an atmosphere containing between 3 and 100%hydrogen, thereby performing a hydrogenation process on the activelayer. This process is one of terminating dangling bonds in thesemiconductor layer by hydrogen which is thermally excited. Plasmahydrogenation (using hydrogen which is excited by a plasma) ma also beperformed as another means of hydrogenation.

An opening portion 415 for reaching a source region and a drain regionof the TFT (see FIG. 9A) and source and drain wirings 416 are formed.(See FIG. 9B.) Further, although not shown in the figures, in thisembodiment, the wirings are three layer structure lamination films inwhich a 100 nm Ti film, a 300 nm aluminum film containing Ti, and a 150nm Ti film are formed in succession by sputtering.

A silicon nitride film, a silicon oxide film, or a silicon oxynitridefilm is formed next at a thickness of 50 to 500 nm (typically between200 and 300 nm) as a passivation film 417. (See FIG. 9C.) Plasmaprocessing is performed earlier than film formation in this embodimentusing a gas containing hydrogen such as H₂, NH₃ and the like, and heattreatment processing is performed after the film formation. Hydrogenexcited by this preprocess is supplied throughout the third insulationfilm 414. By performing heat treatment in this state, the film qualityof the passivation film 417 is improved, and the amount of hydrogenadded to the third insulation film 414 diffuses to the lower side, andtherefore the activation layer can be effectively hydrogenated.

Further, additional hydrogenation processing may also be performed afterforming the passivation film 417. For example, heat treatment may beperformed for 1 to 12 hours at 300 to 450° C. in an atmospherecontaining between 3 and 100% hydrogen. Alternatively, a similar effectcan also be obtained by using plasma hydrogenation.

A fourth insulation film 418 made from an organic resin is then formedhaving a thickness of approximately 1 μm as a leveling film. (See FIG.9C.) Materials such as polyimide, acrylic, polyamide, polyimide amide,and BCB (benzocyclobutene) can be used as the organic resin. Thefollowing can be given as advantages of using an organic resin film: thefilm formation method is simple; the dielectric constant is low, andtherefore the parasitic capacitance is low; and there is superiorlevelness. Note that organic resin films other than those stated above,such as organic SiO compounds, can also be used. A thermalpolymerization type polyimide is used here, and it is formed by tiringat 300° C. after application to the substrate.

A second substrate 419 is prepared next. An adhesive 420 is applied toregions in which the thin film device is not formed when the secondsubstrate 419 is joined to the first substrate 400, and a viscousadhesive 421 is applied to other regions so that a polarization film 422does not move. (See FIG. 9D.)

A glass substrate, a quartz substrate, and in addition, substrates suchas a silicon substrate, a metallic substrate, and a stainless steelsubstrate can be used as the second substrate 419. Further, the adhesive420 bonds portions which are later cut away (regions in which the thinfilm device is not formed), and therefore it is not necessary for theadhesive 420 to be transparent. One having resistance to heat may beselected. For example, there are polyvinyl alcohol (PVA) adhesivesgenerally used in bonding polarization films. An adhesive havingresistance to heat and which is transparent is effectively used as theviscous adhesive 421, and acrylics, urethanes, and silicon adhesives canbe given as viscous adhesives.

The surface of the first substrate 400 on which the TFT is formed, andthe surface of the second substrate 419 to which the polarization filmis attached, are bonded in FIG. 10A. A transparent, heat resistantadhesive, a polyvinyl alcohol (PVA) adhesive, for example, may be usedas the adhesive.

The first substrate 400 is then cut away using means such as backgrinding or CMP, with the thin film device retained on the secondsubstrate 419. (See FIG. 10B.) A quartz substrate is used as the firstsubstrate 400, and a nitride film is used as the etching stopper 401 inthis embodiment, and therefore wet etching using hydrofluoric acid isperformed as a final removal means. Note that portions of the firstsubstrate 400 may be left when patterning using wet etching, and thatthese portions can be used as liquid crystal display device spacers.Further, the etching stopper 401 made from a nitride film may also beremoved subsequently by dry etching in this embodiment.

An opening portion is formed next in the first insulation film 402 inorder to make the to a pixel electrode, and a pixel electrode 423 isformed. (See FIG. 10B.) The pixel electrode 423 may be formed by using,a transparent conductive film for cases in which a transmission typeliquid crystal display device is formed, and by using a metallic filmfor cases in which a reflection type liquid crystal display device isformed. A transmission type liquid crystal display device is formedhere, and therefore a 110 nm thick indium oxide and tin oxide (ITO) filmis formed by sputtering.

Further, there is a method of forming the conductive connection by thesource and drain wirings 416 of FIG. 9B when an opening portion forreaching the etching stopper 401 is formed in portions other than theactive layer when opening the opening portion 415 for reaching thesource and drain regions of the TFT in FIG. 9A. If this method is used,portions other than the active layer are made conductive, and thereforethe aperture ratio of the pixel drops, but the pixel electrode 423 canbe made level.

Next, although not shown in the figures, an orientation film is formedusing a polyimide film, a rubbing process is performed, and the liquidcrystal molecules are given a certain, fixed pre-tilt angle andoriented. An opposing electrode 425 is then formed on a polarizationfilm 426, and these are joined using a sealing material, spacers, andthe like (both not shown in the figures) in accordance with a known cellconstruction process. Liquid crystals 424 are then sealed using asealant 427. (See FIG. 10C.) Note that it is preferable to form ashielding film on the polarization film 422 if the incidence directionfor light is that of light 1. Further, it is preferable to form a filmwhich becomes a light shielding film above or below the first insulationfilm 402 for cases in which the light incidence direction is light 2.Known liquid crystal materials may be used for the liquid crystals. Notethat one more supporting material similar to the second substrate 419may also be prepared for cases in which the polarization film 426 warps.Color filters and shielding films may also be formed when necessary inthe opposing polarization film 426.

Next, as shown in FIG. 11A, portions bonded by the adhesive 420 are cut.Only portions bonded by the viscous adhesive 421 remain, and thereforethe second substrate 419 is peeled off, and a thin, light weight,flexible active matrix liquid crystal display device is complete. (SeeFIG. 11B.)

In addition, an example of a liquid crystal display device in whichdriver circuit is integrated and manufactured together with the liquidcrystal display device using the manufacturing method of the presentinvention is shown in FIG. 12. FIG. 12 is a diagram showing a stateafter a source signal line driver circuit 1302, a gate signal linedriver circuit 1303, and transistors structuring a pixel portion 1301are formed on a first substrate, after which a second substrate isbonded, the first substrate is removed, and liquid crystals areintroduced (liquid crystal introduced region 1306), as seen from theliquid crystal side.

The liquid crystal display device shown in FIG. 12 is structured by thepixel portion 1301, the source signal line driver circuit 1302, and thegate signal line driver circuit 1303). The pixel portion 1301 is ann-channel TFT, and the driver circuits formed in the periphery arestructured by CMOS circuits as basic elements. The source signal linedriver circuit 1302 and the gate signal line driver circuit 1303 areconnected to all FPC (flexible printed circuit) 1305 by using aconnection wiring 1304, and signals from external driver circuits arereceived.

A cross sectional diagram of FIG. 12 cut along the line A-A′ is shown inFIG. 13. Liquid crystals 1403, surrounded by a polarization film 1401,an opposing electrode 1402, and a sealant 1404, are below a pixelelectrode 1405) connected to a pixel TFT 1406. The liquid crystals 1403are also below the driver TFT 1407 in this case, but the liquid crystals1403 may also be arranged only under the pixel electrode 1405 for caseswhen one wishes to reduce parasitic capacitance. Signals from an FPC1409 bonded by a conductive material 1408 are input to the driver TFT1407. The structure functions as a transmission type display device byforming a polarization film 1410 on the opposite side of thepolarization film 1401, with respect to the liquid crystals 1403.

Embodiment 2

An example of a three dimensional package in which thin film devicesformed using the present invention are overlapped is explained simply inthis embodiment using figures.

Up through the processes of FIG. 9C is similar to Embodiment 1, andtherefore an explanation of those portions is omitted. FIG. 14A is astate nearly identical to FIG. 9A, but the source and drain wiring 416is extended, thereby forming an electrode 900. Note that two transistorsare shown for the explanation, and portions common to Embodiment 1 usethe same reference numerals as Embodiment 1.

An opening portion 901 is formed here, and left such that the conductiveconnection can be made with the electrode 900. (See FIG. 14B.) Theadhesive 420 and the viscous adhesive 421 are applied to the secondsubstrate 419, but the polarization film is not necessary. (See FIG.14C.) The polarization film is not necessary, but a thin plate,protection film, and the like can be used in order to maintain rigidity.In this case, an opening portion is formed in the thin plate orprotecting film in advance in a position corresponding to the openingportion 901. The surface of the first substrate 400 on which the thinfilm device is formed, and the second substrate 419, are bonded usingthe adhesive 420 and the viscous adhesive 421 in FIG. 15A.

Similar to Embodiment 1, the first substrate 400 and the etching stopper401 are removed. An opening portion is formed in the first insulationfilm 402, and an electrode 902 is formed. A passivation film 903 and afifth insulation film 904 are formed with covering the electrode 902,and an opening portion 905 is formed so that the conductive connectionto the electrode 902 can be made. The passivation film 903 may be formedusing a silicon nitride film, a silicon oxide film, or a siliconoxynitride film at a thickness of 50 to 500 nm, (typically between 200and 300 nm), similar to the passivation film 417 of Embodiment 1. Thefifth insulation film 904 is similar to the fourth insulation film 418of Embodiment 1, and it provides leveling as well as being a protectivefilm. The state of FIG. 15B is thus reached by performing the processesthrough here.

The second substrate 419 is then removed by the same method as that ofEmbodiment 1. A plurality of the thin film devices formed by processingup through this point are manufactured, and conductive connections aremade between electrodes by using a conductive paste 906. If the thinfilm devices are then overlapped and joined, a semiconductor devicepackaged in three dimensions is complete. (See FIG. 16.) Large capacity,small size, and light weight have been sought for memory in recentyears, and the utilization of techniques for three dimensional packagingare in the spotlight. Semiconductor devices that are packaged in threedimensions can easily be realized, without making the process steps morecomplex, if the present invention is used. Note that the joined thinfilm devices are shown in FIG. 16 with conductive connections madethrough the source and drain regions of the thin film transistors, butdirect connections of wirings may also be made.

Embodiment 3

A semiconductor device using thin film transistors (TFTs) which usesemiconductor thin films formed on an insulator in their active layersis explained in this embodiment. Note that, although a cross section ofone thin film transistor portion and wirings is shown in the figures inorder to explain the positional relationships such as those betweenwirings and an active layer, and between wirings and insulation films,the present invention can also be applied to an integrated circuithaving a plurality of thin film transistors.

A glass substrate or a quartz substrate can be used as a first substrate2401 in FIG. 17A. In addition, substrates having an insulation filmformed on their surfaces, such as a silicon substrate, a metallicsubstrate, or a stainless steel substrate, can also be used.

An etching stopper 2402 is formed next for removal of the firstsubstrate 2401. A material having a selectivity which is sufficientlylarge with respect to the first substrate is used for the etchingstopper 2402. A quartz substrate is used as the first substrate 2401,and a nitride film having a thickness of 10 to 1000 nm (typicallybetween 100 and 500 nm) is formed as the etching stopper 2402 in thisembodiment.

A lower portion insulation film 2403 is formed on the etching stopper2402 from a 10 to 100 nm thick (typically 300 to 500 nm thick) siliconoxide film. Further, a silicon oxynitride film may also be used.

Subsequently, a 10 to 100 nm thick amorphous semiconductor film (anamorphous silicon film 2404 in this embodiment) is formed by a knownfilm formation method on the lower portion insulation film 2403. (SeeFIG. 17B.) Note that, in addition to the amorphous silicon film, anamorphous compound semiconductor film such as amorphous silicongermanium can also be used as the amorphous semiconductor film.

A semiconductor film containing a crystalline structure (a crystallinesilicon film 2405 in this embodiment) is then formed in accordance withthe technique recorded in Japanese Patent Application Laid-open No.7-130652 (U.S. Pat. No. 5,643,826). The technique recorded in the abovepatent is a means of crystallization using a catalyst element (oneelement, or a plurality of elements, selected from the group consistingof nickel, cobalt, germanium, tin, lead, palladium, iron, and copper,typically nickel) for promoting crystallization when crystallizing anamorphous silicon film.

Specifically, heat treatment is performed in a state in which thecatalyst element is retained in the surface of the amorphous siliconfilm, thereby changing the amorphous silicon film to a crystallinesilicon film. The technique recorded in Embodiment 1 of the above patentis used in this embodiment of the present invention, but the techniquerecorded in Embodiment 2 of the patent may also be used. Note thatsingle crystalline silicon films and polycrystalline silicon films arecontained with the term crystalline silicon film, and that thecrystalline silicon film formed in this embodiment is a silicon filmhaving crystal rain boundaries.

Although depending upon the amount of hydrogen contained in theamorphous silicon film, it is preferable to perform dehydrogenationprocessing by heat treatment at 400 to 550° C. for several hours,thereby reducing the amount of contained hydrogen to 5 atomic % or less,and then performing crystallization. Further, other method ofmanufacturing the amorphous silicon film, such as sputtering orevaporation, may also the used: however, it is preferable tosufficiently reduce impurity elements such as oxygen and nitrogencontained within the film.

A known technique may be used on the amorphous silicon film 2404 to formthe crystalline silicon film (polysilicon film or polycrystallinesilicon film) 2405. Light emitted from a laser (hereafter referred to aslaser light) is irradiated to the amorphous silicon film 2404 in thisembodiment, forming the crystalline silicon film 2405. (See FIG. 17C.) Apulse emission type or continuous emission type excimer laser may beused as the laser, and a continuous emission argon laser may also beused. Alternatively, the second harmonic, the third harmonic, or thefourth harmonic of an Nd:YAG laser or an Nd:YVO laser may also be used.In addition, the beam shape of the laser light may be a linear shape(including long and thin shapes) or a rectangular shape.

Furthermore, light emitted from a lamp (hereafter referred to is lamplight) may also be irradiated as a substitute for laser light (hereafterreferred to as lamp annealing). Lamp light emitted from a lamp such as ahalogen lamp or an infrared lamp can be used is the lamp light.

A process of performing thermal processing (annealing) as above by laserlight or lamp light is referred to as an optical annealing process. Theoptical annealing process is performed at a high processing temperaturefor a short time, and therefore the thermal process can be performedeffectively and at high throughput for cases in which a substrate havinglow resistance to heat, such as a glass substrate, is used. Of course,the aim is to perform annealing, and therefore furnace annealing(thermal annealing) can also be performed by using an electric furnaceas a substitute.

Laser annealing is performed in this embodiment using light from a pulseemission excimer laser formed into a linear shape. The laser annealingconditions are as follows: XeCl gas is used as an excitation gas; theprocessing temperature is set to room temperature; the pulse emissionfrequency is set to 30 Hz; and the laser energy density is from 250 to500 mJ/cm² (typically between 350 and 400 mJ/cm²).

Along with the complete crystallization of any amorphous regionsremaining after thermal crystallization, laser annealing performed atthe above conditions has an effect of lowering faults in the crystallineregions already crystallized. This process can therefore also bereferred to as a process for improving the crystallinity of thesemiconductor film by optical annealing, and a process for promotingcrystallization of the semiconductor film. It is also possible to obtainthese types of effects by optimizing the lamp annealing conditions.

A protective film 2406, used during subsequent impurity addition, isformed next on the crystalline silicon film 2405. (See FIG. 17D.) Theprotective film 2406 is formed using a silicon oxynitride film, or asilicon oxide film, having a thickness from 100 to 200 nm (preferablybetween 130 and 170 nm). The protective film 2406 is formed so that thecrystalline silicon film 2405 is not directly exposed to a plasma duringimpurity addition, and in order to make delicate temperature controlpossible.

Subsequently, an impurity element which imparts p-type conductivity(hereafter referred to as a p-type impurity) is added through theprotective film 2406. Typically a periodic table group 13 element,usually boron or gallium, can be used as the p-type impurity element.This process (also referred to as a channel doping process) is one forcontrolling the TFT threshold voltage. Note that Boron is added here byion doping in which a plasma is excited using diborane (B₂H₆) withoutseparation of mass. Ion implantation, in which mass separation isperformed, may of course also be used.

A p-type impurity region (a) 2407 containing a p-type impurity element(boron in this embodiment) at a concentration of 1×10¹⁵ to 1×10¹⁸atoms/cm³ (typically between 5×10¹⁶ and 5×10¹⁷ atoms/cm³) is formed bythis process. (See FIG. 17D.)

Next, after removing the protective film 2406, unnecessary portions ofthe crystalline silicon film are removed to form an island-shapesemiconductor film (hereafter referred to as an active layer) 2408. (SeeFIG. 17E.)

A gate insulation film 2409 is formed with covering the active layer2408. (See FIG. 18A.) The gate insulation film 2409 may be formed havinga thickness of 10 to 200 nm, preferably from 50 to 150 nm. A siliconoxynitride film is formed having a thickness of 80 nm by plasma CVDusing N₂O and SiH₄ as raw materials.

Although not shown in the figures, a two layer lamination film of 50 nmof tungsten nitride (WN) film and 350 nm of tantalum (Ta) is used as agate electrode 2410. (See FIG. 18B.) The gate electrode mar also beformed by a single layer conductive film, but it is preferable to use atwo layer or a three layer lamination film when necessary.

Note that an element selected from the group consisting of tantalum(Ta), titanium (Ti), molybdenum (Mo), tungsten (W), chromium (Cr), andsilicon (Si), or an alloy film of a combination of the above-mentionedelements (typically an Mo—W alloy or an Mo—Ta alloy) can be used as thegate electrode.

Next, an n-type impurity element (phosphorous in this embodiment) isadded in a self aligning manner with the gate wiring 2410 as a mask.(See FIG. 18C.) The addition process is regulated so that phosphorous isadded to an n-type impurity region (a) 2411 thus formed at aconcentration (typically from 1×10¹⁶ to 5×10¹⁸ atoms/cm³, more typicallybetween 3×10¹⁷ and 3×10¹⁸ atoms/cm³) which is from 5 to 10 times higherthan the boron concentration added by the channel doping process.

A resist mask 2412 is formed, an n-type impurity element (phosphorous inthis embodiment) is added, and an n-type impurity region (b) 2413containing a high concentration of phosphorous is formed. (See FIG.18D.) Ion doping using phosphine (PH₃) is performed here (ionimplantation may also be performed, of course), and the concentration ofphosphorous in this region is set from 1×10²⁰ to 1×10²¹ atoms cm³(typically between 2×10²⁰ and 5×10²⁰ atoms/cm³).

Further, phosphorous and boron which have been added in the previousprocess are already contained in regions in which the n-type impurityregion (b) 2413 is formed, but phosphorous is added at a sufficientlyhigh concentration here, and therefore one need not consider theinfluence of phosphorous and boron already added by the prior steps.

After removing the resist mask 2412, a first interlayer insulating film2414 is formed (See FIG. 19A.) An insulation film containing silicon,specifically a silicon nitride film, a silicon oxide film, a siliconoxynitride film, or a lamination film of a combination of these films,may be formed with a thickness of 600 nm to 1.5 μm as the firstinterlayer insulating film 2414. A 1 μm thick silicon oxynitride film(with a nitrogen concentration from 25 to 50 atomic %) is formed in thisembodiment using plasma CVD with SiH₄, N₂O, and NH₃ as raw materialgasses.

A heat treatment process is performed next in order to activate then-type and p-type impurity elements added at their respectiveconcentrations. (See FIG. 19A.) This process can be performed by furnaceannealing, laser annealing, or rapid thermal annealing (RTA). Theactivation process is performed here by furnace annealing. The heattreatment process is performed within a nitrogen atmosphere at 300 to650° C., preferably between 400 and 550° C. Heat treatment is performedhere for 4 hours at 550° C.

The catalyst element used in crystallizing the amorphous silicon film(nickel in this embodiment) moves in the direction shown by the arrow atthis point in this embodiment, and is captured (gettered) in the n-typeimpurity region (b) 2413 containing a high concentration of phosphorousand which is formed by the step shown in FIG. 18D. This is a phenomenacaused by the gettering effect of metallic elements by phosphorous, andas a result, the concentration of the catalyst element in a channelregion 2415 becomes less than or equal to 1×10¹⁷ atoms/cm³ (preferablyless than or equal to 1×10¹⁶ atoms cm³).

Conversely, the catalyst element is segregated in a high concentrationin a region which becomes a gettering site for the catalyst element (then-type impurity region (b) 2413 formed by the step shown in FIG. 18D),and the catalyst element exists there at a concentration greater than orequal to 5×10¹⁸ atoms/cm³ (typically from 1×10¹⁹ to 5×20²⁰ atoms/cm³).

In addition, heat treatment is performed at a temperature of 300 to 450°C. for 1 to 12 hours in an atmosphere containing between 3 and 100%hydrogen, thereby performing a hydrogenation process on the activelayer. This process is one of terminating dangling bonds in thesemiconductor layer by hydrogen which is thermally excited. Plasmahydrogenation (using hydrogen which is excited by a plasma) may also beperformed as another means of the hydrogenation.

An opening portion 2416 for reaching a source region and a drain regionof the TFT (see FIG. 19B), and first wirings 2417 are formed. (See FIG.19C.) Further, although not shown in the figures, in this embodiment,the first wirings are a three layer structure lamination films in whicha 100 nm Ti film, a 300 nm aluminum film containing Ti, and a 150 nm Tifilm are formed in succession by sputtering.

A silicon nitride film, a silicon oxide film, or a silicon oxynitridefilm is formed next at a thickness of 50 to 500 nm (typically between200 and 300 nm) as a passivation film 2418. (See FIG. 19D.) Plasmaprocessing is performed in advance in this embodiment using a gascontaining hydrogen such as H₂, NH₃ and the like, and heat treatmentprocessing is performed after film formation. Hydrogen excited by thispreprocess is supplied throughout the first interlayer insulating film2414. By performing heat treatment in this state, the film quality ofthe passivation film 2418 is improved, and the amount of hydrogen addedto the first interlayer insulating film 2414 diffuses to the lower side,and therefore the activation layer can be effectively hydrogenated.

Further, additional hydrogenation processing may also be performed afterforming the passivation film 2418. For example, heat treatment may beperformed for 1 to 12 hours at 300 to 450° C. in an atmospherecontaining between 3 and 100% hydrogen. Alternatively, similar effectcan also be obtained by using plasma hydrogenation.

A insulation film 2419 made from an organic resin is then formed havinga thickness of approximately 1 μm as a leveling film. (See FIG. 19D.)Materials such as polyimide, acrylic, polyamide, polyimide amide, andBCB (benzocyclobutene) can be used as the organic resin. The followingcan be given as advantages of using an organic resin film: the filmformation method is simple; the dielectric constant is low, andtherefore the parasitic capacitance is low; and there is superiorlevelness. Note that organic resin films other than those stated above,such as organic SiO compounds, can also be used. A thermallypolymerization type polyimide is used here, and it is formed by firingat 300° C. after application to the substrate.

A second substrate 2420 is prepared next, and bonded to the surface ofthe first substrate 2401 on which the thin film device is formed. Aglass substrate, a quartz substrate, and in addition, substrates such asa silicon substrate, a metallic substrate, and a stainless steelsubstrate can be used as the second substrate 2420 here. A quartzsubstrate is used as the second substrate 2420 in this embodiment.Adhesives such as epoxies, cyanoacrylates, and light hardening adhesivescan be used as the adhesive here.

The first substrate 2401 is then cut away using means such as backgrinding or CMP (chemical mechanical polishing), with the thin filmdevice retained on the second substrate 2420. (See FIG. 20B.) A quartzsubstrate is used as the first substrate 2401, and a nitride film isused as the etching stopper 2402 in this embodiment, and therefore wetetching using hydrofluoric acid is performed after grinding to asuitable thickness. Further, the nitride film etching stopper 2402 mayalso be removed subsequently by dry etching in this embodiment.

An opening portion 2421 is formed next in the lower portion insulationfilm 2403 in order to connect to the active layer 2408 (see FIG. 20B),and second wirings 2422 and an insulation film 2423 are formed. (SeeFIG. 20C.) Heat treatment of the active layer 2408 is already complete,and therefore a wiring material having a low resistance to heat can beused as the second wirings 2422. Aluminum may be used, similar to thefirst wirings 2417, and indium tin oxide (ITO) may also be used forcases in which the thin film device is used as a transmission typeliquid crystal display device, as shown in Embodiment 4.

The thickness of the insulation film between the first wiring 2417 andthe second wiring 2422 can thus be made thicker, and parasiticcapacitance can be reduced, using the manufacturing of the presentinvention. There are no problems in forming conductive connectionsthrough the insulation film, and further, a wiring material having lowheat resistance can be used. This contributes to high speed circuitoperation of electric circuits and to accurate propagation of electricsignals.

Embodiment 4

A process of manufacturing an active matrix liquid crystal displaydevice from the semiconductor device manufactured by Embodiment 3 isexplained in this embodiment. As shown in FIG. 21 the second wirings2422 is formed with respect to the substrate in the state of FIG. 20B. Atransparent conductive film may be used as the second wirings 2422 forcases of manufacturing a transmission type liquid crystal displaydevice, and a metallic film may be used if a reflection type liquidcrystal display device is manufactured. An indium tin oxide (ITO) filmis formed by sputtering to a thickness of 110 nm here because atransmitting type liquid crystal display device is made.

An orientation film 801 is formed A polyimide film is used as theorientation film over this embodiment. Further, an opposing electrode804 and an orientation film 803 are formed in an opposing substrate 805.Note that color filters and light shielding films may also be formedover the opposing substrate when necessary.

A rubbing process is performed after forming the orientation film 803,so as to orient liquid crystal molecules by giving them a certain,fixed, pre-tilt angle. The active matrix substrate on which the pixelportion and a driver circuit are formed (the semiconductor devicemanufactured in this embodiment 3) and the opposing substrate are thenjoined together through a sealing material, spacers (both not shown inthe figures), and the like, in accordance with a known cell constructiontechnique. Liquid crystals 802 are then injected between both of thesubstrates, and are completely sealed using a sealant (not shown in thefigures). Known liquid crystal materials may be used for the liquidcrystals. The active matrix liquid crystal display device shown in FIG.21 is thus complete.

The overall structure for a case in which a driver circuit is integratedwith this active matrix liquid crystal display device is shown in FIG.22. Note that FIG. 23 is a cross sectional diagram of FIG. 22 cut alongthe line A-A′. FIG. 22 is a diagram showing a state after a sourcesignal line driver circuit 1902, a gate signal line driver circuit 1903,and transistors structuring a pixel portion 1901 are formed on a firstsubstrate, after which a second substrate is bonded, the first substrateis removed, and liquid crystals are introduced (liquid crystalintroduced region 1906), as seen from the liquid crystal side.

The liquid crystal display device shown in FIG. 22 is structured by thepixel portion 1901, the source signal line driver circuit 1902, and thegate signal line driver circuit 1903. The pixel portion 1901 isn-channel TFTs, and the driver circuits formed in the periphery arestructured by CMOS circuits as basic elements. The source signal linedriver circuit 1902 and the gate signal line driver circuit 1903 areconnected to an FPC (flexible printer circuit) 1905 by using aconnection wiring 1904, and signals from external driver circuits arereceived.

Liquid crystals 1002, surrounded by an opposing electrode 1001 and asealant 1003, are below a pixel electrode 1004 connected to a pixel TFT1005). The liquid crystals 1002 are also below a driver TFT 1006 in thiscase, but the liquid crystals 1002 may also be arranged only under thepixel electrode 1004 for cases when one wishes to reduce parasiticcapacitance. Signals from an FPC 1008 bonded by a conductive material1007 are input to the driver TFT 1006.

Embodiment 5

An example of applying the manufacturing method of the semiconductordevice of the present invention to an active matrix type EL (electroluminescence) display device will be described.

The manufacturing steps are same as that till shown in FIG. 10B ofEmbodiment 1. However the polarized film 422 is not necessary. (FIG.24A.) A transparent conductive film having a large work coefficient isused as the pixel electrode 1200. A chemical compound of indium oxideand tin oxide or a chemical compound of indium oxide and zinc oxide canbe used as the transparent conductive film.

The fifth insulating film 1202 is then formed on the pixel electrode1200, (below the pixel electrode in the figure) and an open portion isformed in the fifth insulating film 1202 on the pixel electrode 1200. AnEL layer 1201 is formed on the pixel electrode 1200 in the open portion.Known organic EL materials and known inorganic materials can be used forthe EL layer 1201. Further, low molecular weight (monomer) materials andhigh molecular weight (polymer) materials exist as organic EL materials,and either may be used.

A known application technique may be used as a method of forming the ELlayer 1201. Further, the structure of the EL layer may be a laminationstructure or a single layer structure, in which hole injecting layers,hole transporting layers, light emitting layers, electron transportinglayers, and electron injecting layers are freely combined.

A cathode 1203 composed of a conducting film having light shieldingproperties (typically a conductive film having aluminum, copper, orsilver as its main constituent, or a lamination film of these andanother conductive film) is formed on the EL layer 1201 (below the ELlayer in the figure). Furthermore, it is preferable to remove, as muchas possible, moisture and oxygen existing in the interface between thecathode 1203 and the EL layer 1201. It is therefore necessary to employa scheme such as forming the EL layer 1201 and the cathode 1203 insuccession within a vacuum, or one in which the EL layer 1201 is formedin a nitrogen or inert gas environment, and then the cathode 1203 isformed without exposure to oxygen or moisture. It is possible to performthe above stated film formation in Embodiment 5 by using a multi-chambermethod (cluster tool method) film formation apparatus.

An EL element composed of the pixel electrode 1200, the EL layer 1201,and the cathode 1203 is thus formed. The EL element is enclosed by thefiller material 1204. (FIG. 24B)

A glass plate, a metallic plate (typically a stainless steel material),a ceramic plate, an FRP (fiberglass reinforced plastics) plate, a PVF(polyvinyl fluoride) film, a mylar film, a polyester film, and anacrylic resin film can be used as the cover material 1205. Further, asheet having a structure in which aluminum foil is sandwiched by a PVFfilm or a mylar film can also be used.

Note that, it is necessary for the cover material to be transparent forcases in which the irradiating direction of light from the EL elementsis toward the cover material side. A transparent material such as aglass plate, a plastic plate, a polyester film, or an acrylic film, isused in this case.

Further, an ultraviolet hardening resin or a thermally hardening resincan be used as the filler material 1204. PVC (polyvinyl chloride),acrylic, polyimide, epoxy resin, silicon resin, PVB (polyvinyl butyral)and EVA (ethylene vinyl acetate) can be used. Deterioration of the ELelements can be suppressed if a drying agent (preferably barium oxide)is formed on the inside of the filler material 1204.

Furthermore, spacers may also be included within the filler material1204. It is possible to give the spacers themselves moisture absorbencyban forming the spacers from barium oxide. Further, when formingspacers, it is also effective to form a resin film on the cathode 1203as a buffer layer for relieving pressure from the spacers.

Lastly, the second substrate 419 is removed by cut a substrate same asEmbodiment 1. Thin and light active matrix EL display device is thusmanufactured. (FIG. 24C.)

Embodiment 6

An example of manufacturing an EL (electro luminescence) display deviceusing the present invention in this embodiment will be described. FIG.35 is a diagram showing a state after a source signal line drivercircuit 2102, a gate signal line driver circuit 2103, and transistorsstructuring a pixel portion 2101 are formed on the first substrate and,after which the second substrate is bonded, the first substrate isremoved, and the EL laser is formed, as seen from the EL layer side.FIG. 26 is a cross-sectional diagram of FIG. 11 cut along the line A-A′.

In FIGS. 25 and 26, reference numeral 2201 denotes a substrate,reference numeral 2101 denotes a pixel portion, reference numeral 2102denotes a source signal line driver circuit, 2103 denotes a gate signalline driver circuit. Each of the drivel circuits is connected to anexternal equipment via a connection wiring 2104 leading to an FPC(flexible printed circuit) 2105.

A first sealing material 2106, a cover material 2107, a filler material2208, and a second sealing material 2108 are formed at this point so asto surround the pixel portion 2101, the source signal line drivercircuit 2102, and the gate signal line driver circuit 2103.

FIG. 26 is a cross sectional diagram corresponding to FIG. 25 cut alongthe line A-A′. A driver TFT 2202 (note that an n-channel TFT and ap-channel TFT are shown here) contained in the source signal line drivercircuit 2102 over the substrate 2201, and a pixel TFT 2203 (a TFT forcontrolling the electric current flowing in an EL element is shown here)contained in the pixel portion 2101 are formed.

A pixel electrode 2204 is formed so as to electrically be connected toeither a source region or a drain region of the pixel TFT 2203. Atransparent conductive film having a large work coefficient is used asthe pixel electrode 2204. A chemical compound of indium oxide and tinoxide or a chemical compound of indium oxide and zinc oxide can be usedas the transparent conductive film.

An insulating film 2205 is then formed on the pixel electrode 2204(below the pixel electrode in the figure) and an open portion is formedin the insulating film 2205 over the pixel electrode 2204. An EL layer2206 is formed on the pixel electrode 2204 in the open portion. Knownorganic EL materials and known inorganic materials can be used for theEL layer 2206. Further, low molecular weight (monomer) materials andhigh molecular weight (polymer) materials exist as organic EL materials,and either may be used.

A known application technique may be used as a method of forming the ELlayer 2206. Further, the structure of the EL layer may be a laminationstructure or a single layer structure, in which hole injecting layers,hole transporting lasers, light emitting layers, electron transportinglayers, and electron injecting layers are freely combined.

A cathode 2207 composed of a conducting film having light shieldingproperties (typically a conductive film having aluminum, copper, orsilver as its main constituent, or a lamination film of these andanother conducting film) is formed on the EL layer 2206. Furthermore, itis preferable to remove, as much as possible, moisture and oxygenexisting in the interface between the cathode 2207 and the EL layer2206. It is possible to perform the above stated film formation inEmbodiment 6 by using a multi-chamber method cluster (tool method) filmformation apparatus.

An EL element composed of the pixel electrode 2204, the EL layer 2206,and the cathode 2207 is thus formed. The EL element is surrounded by thecover material 2107 which is joined to the substrate 2201 by the firstsealing material 2106 and the second sealing material 2108 and isenclosed by, the filler material 2208.

A glass plate, a metallic plate (typically a stainless steel plate), aceramic plate, an FRP (fiberglass reinforced plastics) plate, a PVF(polyvinyl fluoride) film, a mylar film, a polyester film, and anacrylic resin film can be used as the cover material 2107. Further, asheet having a structure in which aluminum foil is sandwiched by a PVFfilm or a mylar film can also be used.

Note that, it is necessary for the cover material to be transparent forcases in which the irradiating direction of light from the EL elementsis toward the cover material side. A transparent material such as aglass plate, a plastic plate, a polyester film, or an acrylic film, isused in this case.

Further, an ultraviolet hardening resin or a thermally hardening resincan be used as the filler material 2208. PVC (polyvinyl chloride),acrylic, polyimide, epoxy resin, silicon resin, PVB (polyvinyl butyral)and EVA (ethylene vinyl acetate) can be used. Deterioration of the ELelements can be suppressed if a drying agent (preferably barium oxide)is formed on the inside of the filler material 2208.

Furthermore, spacers may also be included within the filler material2208. It is possible to give the spacers themselves moisture absorbencyby forming the spacers from barium oxide. Further, when forming spacers,it is also effective to form a resin film on the cathode 2207 as abuffer layer for relieving pressure from the spacers.

The connection wiring 2104 is electrically connected to the FPC 2105through a conductive material 2209. The connection wiring 2104 transmitssignals sent to the pixel portion 2101, the source signal line drivercircuit 2102, and the gate signal line driver circuit 2103 to the FPC2105, and the wiring is electrically connected to external equipment bythe FPC 2105.

Further, the second sealing material 2108 is formed so as to coverexposed portions of the first sealing material 2106 and a portion of theFPC 2105, resulting in a structure in which the EL elements arecompletely cutoff from the atmosphere. This becomes the EL displaydevice having the cross sectional structure of FIG. 26.

Embodiment 7

A method of forming a bottom gate thin film transistor using themanufacturing method of the present invention is explained simply inthis embodiment. A cross sectional diagram of one transistor portion isshown in FIG. 27, and the method of manufacture is basically the same asthat of Embodiment 3. Note that the term bottom gate thin filmtransistor indicates a thin film transistor having a shape in which anactive layer is formed in a layer between a gate electrode and a secondwiring (the gate electrode and the wiring are not formed on the sameside of the active layer), as shown in FIG. 27, in this specification.

An impurity is added to the active layer 2408 in a self aligning mannerwith the are electrode 2410 as a mask, similar to Embodiment 1, in FIG.18C. The first wiring 2417 is not necessary, and therefore thepassivation film 2418 and the insulation film 2419 are formed on thegate electrode 2410, thereby performing leveling. The second substrate2420 is bonded next, the first substrate 2401 is removed, and the secondwiring 2422 (denoted as the second wiring in order to be compatible withEmbodiment 3, although the first wiring does not exist in thisembodiment) and the insulation film in are foil formed.

A bottom gate transistor possessing a wiring and a gate electrode onopposite sides of an active layer can thus be formed. Different from aconventional bottom gate transistor, an impurity can be added in a selfaligning manner.

Embodiment 8

The active matrix display device manufactured by employing the presentinvention may be used as a display portion of electric equipment. Assuch electric equipments, there are given a video camera, a digitalcamera, a projector, a projection TV, a goggle type display (head mountdisplay), a navigation system, a sound reproduction device, a note typepersonal computer, a game device, a portable information terminal (suchas a mobile computer, a cell phone, a portable type game device or anelectronic book), an image playback device having a recording medium,and the like. Specific examples of such electric equipments are given inFIGS. 28A to 28F.

FIG. 8A shows a cell phone that is composed of a main body 300, a voiceoutput portion 3002, a voice input portion 3003, a display portion 3004,operating snitches 3005, and an antenna 3006. The active matrix displaydevice of the present invention may be used in the display portion 3004.

FIG. 28B shows a video camera that is composed of a main body 3101, adisplay portion 3102, a sound input portion 3103, operation switches3104, a battery 3105, and an image receiving portion 3106. The activematrix display device of the present invention may be used in thedisplay portion 3102.

FIG. 28C shows a mobile computer that is composed of a main body 3201, acamera portion 3202, an image receiving portion 3203, an operatingswitch 3204 and a display portion 3205. The active matrix display deviceof the present invention may be used in the display portion 3205.

FIG. 28D shows a goggle type display that is composed of a main body3301, display portions 3302 and arm portions 3303. The active matrixdisplay device of the present invention may be used as the displayportions 3302.

FIG. 28E shows a rear projector (projection TV) which is composed of amain body 3401, a light source 3402, a liquid crystal display device3403, a polarized light beam splitter 3404, reflectors 3405, 3406, and ascreen 3407. The present invention man be applied to the liquid crystaldisplay device 3403.

FIG. 28F shows a front projector which is composed of a main body 3501,a light source 3502, a liquid crystal display device 3503, an opticalsystem 3504 and a screen 3505. The present invention may be applied tothe liquid crystal display device 3503.

As described above, the application range of the present invention isextremely wide, and may be applied to electric equipments in all fields.

A semiconductor device can be made thinner, lighter weight, and beimparted with flexibility with the present invention. In general, theprocess of manufacturing a semiconductor device is complex if asubstrate is made thinner, but the semiconductor device can be easilymanufactured by using a suitable supporting material only duringmanufacture in the present invention. It is possible to apply thepresent invention to semiconductor devices in which circuits such as SOIstructure integrated circuits, active matrix liquid crystal displaydevices, and active matrix EL display devices are formed on aninsulator. Further, insulation films between wirings can be made thickerby using the present invention, and parasitic capacitance generatingbetween wirings formed on different layers can be reduced. In addition,the problem of making conductive connections by forming an openingportion in an insulation film, and the problem of wiring material heatresistance when insulation films are formed thicker with a conventionalstructure are solved.

1. A semiconductor device comprising: a first thin film device; a secondthin film device formed over the first thin film device; a third thinfilm device formed over the second thin film device, each of the first,second, and third thin film devices comprising: a first insulating film;a first electrode formed over the first insulating film; a secondinsulating film formed over the first electrode; first and second thinfilm transistors formed over the second insulating film, wherein thefirst thin film transistor is connected to the first electrode through afirst contact hole; a third insulating film formed over the first andsecond thin film transistor; a second electrode formed over the thirdinsulating film, wherein the second electrode is connected to the secondthin film transistor through a second contact hole; and a fourthinsulating film formed over the third insulating film and the secondelectrode, wherein the second electrode of the first thin film device iselectrically connected to the first electrode of the second thin filmdevice, and wherein the second electrode of the second thin film deviceis electrically connected to the first electrode of the third thin filmdevice.
 2. An electric equipment having the semiconductor deviceaccording to claim 1, wherein the electric equipment is one selectedfrom the group consisting of a cell phone, a video camera, a digitalcamera, a projection TV, a navigation system, a game machine, a portabletype game device, a sound reproduction device, an electronic book, animage playback device having a recording medium, a mobile computer, agoggle type display, a rear projector, and a front projector.
 3. Asemiconductor device according to claim 1, wherein the semiconductordevice is an active matrix liquid crystal display device.
 4. Asemiconductor device according to claim 1, wherein the semiconductordevice is an EL display device.
 5. A semiconductor device according toclaim 1, further comprising: first and second conductive pastes, whereinthe second electrode of the first thin film device is electricallyconnected to the first electrode of the second thin film device by thefirst conductive paste, and wherein the second electrode of the secondthin film device is electrically connected to the first electrode of thethird thin film device by the second conductive paste.
 6. Asemiconductor device according to claim 1, wherein the first insulatingfilm is a passivation film.
 7. A semiconductor device according to claim1, wherein the first thin film device is overlapped with the second thinfilm device and the third thin film device.
 8. A semiconductor devicecomprising: a first thin film device; a second thin film device formedover the first thin film device; a third thin film device formed overthe second thin film device, each of the first, second, and third thinfilm devices comprising: a first insulating film comprising an organicresin; a second insulating film formed over the first insulating film; afirst electrode formed over the second insulating film; a thirdinsulating film formed over the first electrode; first and second thinfilm transistors formed over the third insulating film, wherein thefirst thin film transistor is connected to the first electrode through afirst contact hole; a fourth insulating film formed over the first andsecond thin film transistor; a second electrode formed over the fourthinsulating film, wherein the second electrode is connected to the secondthin film transistor through a second contact hole; a fifth insulatingfilm formed over the fourth insulating film and the second electrode;and a sixth insulating film comprising an organic resin formed over thefifth insulating film, wherein the second electrode of the first thinfilm device is electrically connected to the first electrode of thesecond thin film device, and wherein the second electrode of the secondthin film device is electrically connected to the first electrode of thethird thin film device.
 9. An electric equipment having thesemiconductor device according to claim 8, wherein the electricequipment is one selected from the group consisting of a cell phone, avideo camera, a digital camera, a projection TV, a navigation system, agame machine, a portable type game device, a sound reproduction device,an electronic book, an image playback device having a recording medium,a mobile computer, a goggle type display, a rear projector, and a frontprojector.
 10. A semiconductor device according to claim 8, wherein thesemiconductor device is an active matrix liquid crystal display device.11. A semiconductor device according to claim 8, wherein thesemiconductor device is an EL display device.
 12. A semiconductor deviceaccording to claim 8, further comprising: first and second conductivepastes, wherein the second electrode of the first thin film device iselectrically connected to the first electrode of the second thin filmdevice by the first conductive paste, and wherein the second electrodeof the second thin film device is electrically connected to the firstelectrode of the third thin film device by the second conductive paste.13. A semiconductor device according to claim 8, wherein the secondinsulating film is a passivation film.
 14. A semiconductor deviceaccording to claim 8, wherein the first thin film device is overlappedwith the second thin film device and the third thin film device.